Polyrotaxane is comprised of a pseudopolyrotaxane, which comprises a linear molecule (axis) and a cyclic molecule(s) (rota) in which the linear molecule is included in cavity (cavities) of the cyclic molecule(s) in a skewered manner, and capping groups, each of which locates at each end of the pseudopolyrotaxane (each end of the linear molecule) in order to prevent the dissociation of the cyclic molecule(s). For example, a polyrotaxane having α-cyclodextrin(s) (hereinafter cyclodextrin may be simply abbreviated as “CD”) as the cyclic molecule(s), and polyethylene glycol (hereinafter may be abbreviated as “PEG”) as the linear molecule has been intensively studied in recent years for its various characteristics (for example, see Patent Document 1).
Further, Patent Document 2 discloses a compound comprising a crosslinked polyrotaxane having a property of a so-called slipping gel or sliding gel, or a property of viscoelastic material. In particular, Patent Document 2 specifically discloses crosslinked polyrotaxane in which polyrotaxanes, each of which comprises α-CD(s) as the cyclic molecule(s) and PEG as the linear molecule which is included in the α-CD(s), are crosslinked (bound) through a chemical binding.
A material comprising a crosslinked polyrotaxane is required to have further improved swelling property. For example, a material comprising a cross linked polyrotaxane which significantly changes in swelling property with change in an environment surrounding the crosslinked polyrotaxane, especially changes in an environmental pH and/or ionic strength, is required. A material comprising a crosslinked polyrotaxane which is responsive especially at a high speed to change in the surrounding electric field is also required.
Patent Document 1: Japanese Patent No. 2810264.
Patent Document 2: Japanese Patent No. 3475252.